Opera 7 is a browser. I think it's put out by a Norweigian company. It is a browser that is suspected of becoming a leader over Netscape. I find that really unlikely though. Netscape 7 has many more feature, has a more reputable name, the full version is free (Opera costs something). IE will always be the top browser since it has simplicity (which neihter opera nor netscape have) comes with Windows, has support for the latest scripting, and everyone has it. I've heard, however, that Opera hasn't kept up with the newer XML/DHTML and CGI routines that are out there.
In my opinion, if you want simplicity, get IE 6. If you want feature, get Netscape 7.
If you want fresh underwear in the morning, take it off the night before.